Lymph . Lymph nodes can become enlarged for many reasons. They are often enlarged when an infection is present in or near them.(tonsils are lymph nodes inthe throat and become enlarged when you have a throat infection) when they enlarge due to infection they usually swell quickly an are painful or at least tender when touched. They also tend to shrink back to normal size after the infection resolves. Lymph nodes that enlarge slowly and remain enlarged for more than about a month are more worrisome including the possibility of cancer or some chronic inflammatory conditions such as lupus or sarcoidosis.